Valve bridge for valve systems

ABSTRACT

A valve bridge for a valve system of an engine includes one or more valves and a valve rotator coupled to the valves. The valve bridge includes one or more end portions, a seat formed at the one or more end portions to receive the one or more valves, and an extension portion that extends outwardly from the one or more end portions. The extension portion defines a cavity configured to accommodate the valve rotator, and guide the valve bridge with the valve rotator during each opening and closing of the one or more valves relative to the engine.

TECHNICAL FIELD

The present disclosure relates to valve systems for internal combustionengines. More particularly, the present disclosure relates to a valvebridge that includes a guide structure for guiding the valve bridge withone or more valves of the valve system.

BACKGROUND

When a cylinder applied in an internal combustion engine is equippedwith more than one of the same type of gas exchange valves (e.g., morethan one intake valve and/or more than one exhaust valve), all valves ofthe same type are typically opened and closed at about the same time. Inorder to reduce a number of camshafts, cam lobes, rocker arms, and/orthe like components, required to open the valves, a valve bridge isoften used to interconnect the same type of valves with a common rockerarm. Valve bridges are typically actuated by a rocker arm, to contactterminal ends of valve stems associated with the same type of valves tocause the valves to synchronously operate between an open and a closedposition. Typically, the rocker arm articulates and executes ato-and-fro motion and slides against the valve body to cause the valvebody to reciprocate relative to the cylinder. During a sliding motion,however, a point of contact between the rocker arm and the valve bridgemay dynamically change. As a result, the rocker arm may distributeunequal forces and stresses to the valve bridge causing the valve bridgeto tilt in one or more dimensions. Such a situation may in turn increasethe chances for the valve bridge to be dislodged or be unseated from thevalves, leading to increased chances of a dropped valve.

U.S. Pat. No. 7,984,705 ('705 reference) relates to an Engine BrakingApparatus with Two-Level Pressure Control Valves. The '705 referencediscloses a valve bridge that is supported by two spring seats. Asupporting spring is used to bias the spring seat to a spring retainerthat acts as a guide to a sliding of the spring seat.

SUMMARY OF THE INVENTION

In one aspect, the disclosure is directed towards a valve bridge for avalve system of an engine. The valve system includes one or more valvesand a valve rotator coupled to the one or more valves. The valve bridgeincludes one or more end portions. A seat is formed at the end portionsto receive the valves. An extension portion extends outwardly from theend portions. Further, a cavity is defined within the extension, andwhich is configured to accommodate the valve rotator, and guide thevalve bridge with the valve rotator during each opening and closing ofthe one or more valves relative to the engine.

In another aspect, the disclosure relates to a valve system for anengine. the valve system includes one or more valves, a valve rotatorcoupled to the one or more valves, and a valve bridge. The valve bridgeincludes one or more end portions, an extension portion extendingoutwardly from the one or more end portions and defining a cavity withinthe extension portion. The cavity is configured to accommodate the valverotator, and guide the valve bridge with the valve rotator during eachopening and closing of the one or more valves relative to the engine.

In yet another aspect, the disclosure is directed to a valve bridge fora valve system of an engine. The valve bridge includes a tappet head, afirst arm and a second arm radially extending away from the tappet headto respectively define a first end portion and a second end portion.Further, the valve bridge includes a seat formed at each of the firstend portion and the second end portion that are configured to receive agas exchange valve of the engine. An extension portion extends outwardlyfrom each of the first end portion and the second end portion, and eachof the first end portion and the second end portion defines a cavity.The cavity is configured to accommodate a valve rotator coupled to thegas exchange valve, and guide the valve bridge with the valve rotatorduring each opening and closing of the gas exchange valve relative tothe engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exemplary engine system including avalve system, in accordance with the concepts of the present disclosure;and

FIG. 2 is a cross-sectional view of the valve system, with certainsurrounding components removed, in accordance with the concepts of thepresent disclosure; and

FIG. 3 is a perspective view of the valve system, in accordance with theconcepts of the present disclosure.

DETAILED DESCRIPTION

Referring to FIG. 1, an engine system 100 is illustrated. The enginesystem 100 includes an engine 102 and a valve system 104 of the engine102. The engine system 100 may be applied in machines such asconstruction machines, generator sets, locomotives, marine applications,and other power based applications. In one example, uses of the enginesystem 100 may also be extended to several domestic and commercialpower-based applications. Reference will now be made in detail tospecific embodiments or features, examples of which are illustrated inthe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or the likeparts.

The engine 102 may be a four-stroke internal combustion engine. However,the engine 102 may also operate according to be a two-stroke principle.In general, the engine 102 may include or represent any type of aninternal combustion engine, including a gasoline engine, aspark-ignition engine, a compression-ignition engine, a gaseousfuel-powered engine, and the like. The engine 102 may include a cylinder108 with a combustion chamber 110. The cylinder 108 may include a piston114 and a connecting rod 116 coupled to the piston 114, as is customary.Although a single cylinder configuration is shown in FIG. 1, the engine102 may include a multi-cylinder configuration, which may be arrangedaccording to one of an “in-line” configuration, a “V” configuration, orany other suitable configuration that follows a general practice of theart. The engine 102 may also include a crankshaft 120 rotatably coupledto the connecting rod 116, as is customary. A sliding (or reciprocal)motion of the piston 114 during a power stroke of the engine 102 resultsin a rotation of the crankshaft 120. Although a configuration of theengine 102 is disclosed, aspects of the present disclosure need not belimited to any particular engine type.

Referring to FIGS. 1, 2, and 3, the valve system 104 is configured toregulate a fluid (fuel or gas) flow into and/or out of the engine 102(or the cylinder 108). The valve system 104 includes one or more valves124, 124′ a set of valve rotators 128, 128′ coupled to the valves 124,124′, a camshaft 130, a cam lobe 132 coupled to the camshaft 130, arocker arm 134, and a valve bridge 136 configured to achieve asimultaneous actuation of the valves 124, 124′.

The valves 124, 124′ are categorized into a first valve 124 and a secondvalve 124′. The first valve 124 and the second valve 124′ may be a fluidexchange valve or a gas exchange valves that facilitate gas exchangebetween the combustion chamber 110 and a gas exchange manifold 140structured within a cylinder head 142 of the engine 102, as shown. Forthe purposes of the present disclosure, a gas exchange may pertain toone of an inflow of fuel or an outflow of combustions gases relative tothe engine 102, and the term ‘gas exchange valves’ may pertain to valvesthat facilitate such inflow and/or outflow. In this regard, the valves124, 124′ may be one of intake valves or exhaust valves, and the gasexchange manifold 140 may be one of an intake manifold or an exhaustmanifold depending upon the type of valves used (i.e. intake orexhaust). A first port 146, and a second port 146′ may be structuredinto the cylinder head 142, or a wall 144 of the cylinder head 142, tofacilitate the gas exchange between the combustion chamber 110 and thegas exchange manifold 140. The first port 146 may include a first valveseat 148. The first port 146 may be selectively closed (i.e. a closedposition) and opened (i.e. an open position) by a reciprocal movement ofthe first valve 124, relative to the engine 102. Similarly, the secondport 146′ may be selectively closed (i.e. a closed position) and opened(i.e. an open position) by a reciprocal movement of the second valve124′, relative to the engine 102. The reciprocal movement of the valves124, 124′ may be synchronous, following a general practice of the art.For clarity and ease in understanding, further description includesdiscussions of a structure and arrangement of the first valve 124 alone.These discussions may be equivalently applied to the second valve 124′as well. Wherever applicable, the second valve 124′ may also bediscussed by way of specific references.

The first valve 124 includes a first disk portion 150, a first valvestem 152, and a first spring 154 arranged around the first valve stem152. In the closed position of the first valve 124, the first diskportion 150 is configured to lock the first port 146 by being engaged orlocked against the first valve seat 148, thereby disallowing the gasexchange to occur through the first port 146. In the open position,conversely, the first disk portion 150 may be disengaged or distancedfrom the first valve seat 148, allowing a gas exchange to occur throughthe first port 146. In both cases, the first valve stem 152 may passthrough the first port 146 and the wall 144 of the cylinder head 142,with the first spring 154 biasing the first valve 124 against the valvebridge 136 and the rocker arm 134. The depicted orientation of the valvesystem 104 of FIGS. 1 and 2 relate to a closed position of the valves124, 124′. Further, the second valve 124′ is similar in form, function,and arrangement, to the first valve 124, and, therefore, the secondvalve 124′ and associated components have been annotated with similarreferences as has been identified of the first valve 124. In thisregard, the second valve 124′ also includes a second disk portion 150′,a second valve stem 152′, and a second spring 154′ arranged around thesecond valve stem 152′.

In some implementations, additional valves may be incorporated into theengine 102 depending upon the engine's output requirement. Further, thegas exchange manifold 140 may also represent or include a number ofmanifolds that facilitate gas exchange. In one exemplary embodiment, thevalves 124, 124′ are intake valves and the gas exchange manifold 140 isan intake manifold. In this regard, the engine 102 may also includeexhaust valves (see FIG. 3, where a first exhaust valve 124 a is shown)and an exhaust manifold (not shown) that is configured to receivecombustion gases from the combustion chamber 110 via the exhaust valves,such as the first exhaust valve 124 a. Although not limited, a number ofexhaust valves, such as the first exhaust valve 124 a, may be equivalentto the number of intake valves (valves 124, 124′) applied.

Referring again to FIG. 1, the camshaft 130 may be coupled to thecrankshaft 120 through a belt drive mechanism or a gear arrangement (notshown), as is well known. In so doing, a rotation of the crankshaft 120may cause a rotation of the camshaft 130, and of the cam lobe 132coupled to the camshaft 130. A rotation of the cam lobe 132 causes anoperation of the valves 124, 124′. More particularly, the cam lobe 132is configured to slide against a cam roller portion 158 of the rockerarm 134 and is adapted to impart a to-and-fro motion to the cam rollerportion 158 (see direction, A). Because the rocker arm 134 may becoupled and pivoted about a rocker shaft 162, as is customary, a fulcrum164 is defined at a junction between the cam roller portion 158 and anopposite end 168 of the rocker arm 134. As a result, the to-and-fromotion (or an oscillation) of the cam roller portion 158 may translateinto a reversed to-and-fro motion (or an inversed oscillation) at theopposite end 168 (see direction, B). The opposite end 168 includes abutton or a tappet contact surface, commonly referred to as an elephantfoot 172 (best shown in FIG. 2). In assembly, the elephant foot 172 isin slidable abutment with a portion (discussed later) of the valvebridge 136. Given such a slidable abutment, the reversed to-and-fromotion (direction, B) of the opposite end 168 may cause the valve bridge136 to reciprocate relative to the engine 102 or the cylinder 108 (seedirection, C), in turn causing the valves 124, 124′ to synchronously(and selectively) vary between the closed position and the open positionrelative to the engine 102 (or the cylinder 108). In course of such areciprocation, the elephant foot 172 may slide back and forth (seedirection, D, FIG. 2) against the portion of the valve bridge 136, withthe rocker arm 134 pushing (or actuating) the valves 124, 124′ in eitherof the open position and/or the closed position, simultaneously.

In some implementations, a motion from the cam lobe 132 to the camroller portion 158 of the rocker arm 134 may be transmitted through apush rod arrangement (not shown). Further, a cam lobe (not shown),similar to the cam lobe 132, may be coupled to the camshaft 130 tofacilitate an operation of the exhaust valves, such as the first exhaustvalve 124 a, as well. A working of such a cam lobe may remain similar toa working of the cam lobe 132, as has been discussed above. In someimplementations, the engine 102 may include multiple cam lobes dependingupon engine specifications and cylinder design. Although details andembodiments of the crankshaft 120, the camshaft 130, and the rocker arm134, have been discussed above, it will be appreciated that thesedetails and embodiments are not limited in any way.

Referring FIGS. 2 and 3, the valve bridge 136 includes a tappet head176, a first arm 178, a second arm 180, a valve bridge stem 182, and aguide structure 184 to facilitate a guiding of the valve bridge 136 withvalves 124, 124′ of the valve system 104. The tappet head 176 may be acentral upstanding rocker arm engaging portion or may include a surface(or portion) to which the elephant foot 172 may be slidably abutted inassembly. Further, the valve bridge 136 includes a base 186, definedoppositely to the tappet head 176. Given the central upstanding rockerarm engaging portion of the tappet head 176, the valve bridge 136 maydefine a generally triangular profile, and according to the depictedorientation, a substantially triangular forward face 190 (or simply aforward face 190) and a substantially triangular rearward face 192 (orsimply a rearward face 192) is defined that impart the characteristictriangular profile to the valve bridge 136. The forward face 190 may bedefined on one side of the valve bridge 136, while the rearward face 192may be defined on an opposite side of the forward face 190 (see FIG. 3),with both the forward face 190 and the rearward face 192 being definedalong substantially parallel planes. Further, the two arms 178, 180(that is the first arm 178 and the second arm 180) may extend radiallyaway from each other, and from the tappet head 176 to define one or moreend portions. The one or more end portions are categorized into a firstend portion 194 and a second end portion 196. A first lateral face 200is defined at the first end portion 194 and a second lateral face 202 isdefined at the second end portion 196. The first lateral face 200 andthe second lateral face 202 are disposed at right angles to the forwardface 190 and the rearward face 192. For the purpose of the presentdisclosure, structural aspects of only the first end portion 194 will befurther discussed. Discussions pertaining to the first end portion 194may be equivalently applicable to the second end portion 196 as well.Wherever applicable, specific references to the second end portion 196may also be used.

The valve bridge 136 may include a first seat 206 formed on the base186, at the first end portion 194. The first seat 206 is configured toreceive the first valve 124. More specifically, the first seat 206includes and/or is structured in the form of a recess or a stem guidepocket that may receive an end 210 (or an upper surface) of the firstvalve stem 152 of the first valve 124, as depicted in FIG. 2. To thisend, a shape of the end 210 of the first valve stem 152 may comply witha shape of the recess (or first seat 206), and may be contouredappropriately to engage the recess of the first seat 206. Such anengagement allows the first seat 206 to guide and save the first valvestem 152 from dislodgement during repeated reciprocation (closure andopening) of the first valve 124. In some embodiments, the recess mayhave a circular shape, such as with a circular cross-section, and may bein the form of a hollow cylinder. Correspondingly, a shape of the firstvalve stem 152, as a whole, or of the end 210 alone, may also becylindrical so as to comply with the inner confines of the recess (firstseat 206).

In some implementations, the recess of the first seat 206 may bemachined or made up of mild steel and manufactured by a milling process.Alternatively, the recess may be manufactured by a single processinvolving casting, for example. In some implementations, the recess maybe omitted from the valve bridge 136 to serve a design requirement, suchas a space constraint, and the like, of the engine system 100. In such acase, the first seat 206 may include no recess at all, and may ratherinclude a flattened surface, flush in relation to a surrounding surfaceof the base 186. In such a case, the end 210 may be unable to extend orbe inserted into the first seat 206 to retain the valve bridge 136, andrather, the end 210 of the first valve stem 152 may simply abut againstthe flattened surface of the first seat 206, in assembly. Therefore,aspects of the present disclosure, directed to the first seat 206 havinga recess, need not be seen as being limiting in any way. Further, asecond seat 206′, similar to the first seat 206 in form and function,may be provided at the second end portion 196, as well.

In some implementations, the tappet head 176 may include a bore 214 (seeFIG. 3) that may accommodate a lash adjuster 216. The lash adjuster 216may be associated with the valve bridge 136 to remove a clearance (orplay) that may exist between the valves 124, 124′ and correspondingseats 206, 206′, and/or between other components of the valve system104, every time the valve bridge 136 is released by the rocker arm 134.Given the provision of the lash adjuster 216, the elephant foot 172 maybe biased into contact with the valve bridge 136 by way of a masterpiston 220 of the lash adjuster 216. It may be noted that the masterpiston 220 may form the portion of the valve bridge 136, as disclosedabove, against which the elephant foot 172 is slidably abutted. Further,the first spring 154 and the second spring 154′ may respectively biasthe valves 124, 124′ against the first valve seat 148, formed on thewall 144 of the cylinder head 142 of the cylinder 108 (FIG. 1), in turnbiasing the valve bridge 136 into contact with the elephant foot 172,and helping the valve bridge 136 remain in contact with the rocker arm134. In some implementations, the bore 214 may be extended into thevalve bridge stem 182 to properly house the lash adjuster 216. Althoughthe valve bridge 136 has been discussed with the assembly of the lashadjuster 216, in some implementations, the lash adjuster 216 may bealtogether omitted. In case of such an omission, the elephant foot 172may slide directly on a surface of the valve bridge 136.

The set of valve rotators 128, 128′ includes a first valve rotator 128and a second valve rotator 128′. The first valve rotator 128 ispositioned around the first valve stem 152, and placed adjacent to theend 210, so that when the first valve 124 is opened and closed, thefirst valve 124 will rotate (see direction, E) a small amount with eachopening and closing. With each reciprocation (see direction, C), sincethe first valve rotator 128 ensures that the first valve 124 rotatesthis small amount, a concentration of a valve defect or deformations ata sole region on the first valve 124, particularly at the first diskportion 150 of the first valve 124, is avoided. The first valve rotator128 may include a circular, dished, or a disk shaped structure, and mayinclude a retainer flange 224 bounded by an offset peripheral flange (orsimply a peripheral flange 226). The retainer flange 224 may be rigidlycoupled to the first valve stem 152 at a portion adjacent to the end210, while the retainer flange 224 may be press fitted into theperipheral flange 226. The peripheral flange 226 includes a flatcircular portion termed as a circular shoulder 228, where an upper end230 of the first spring 154 (as seen in the orientation of the FIGS. 1,2, and 3) may be seated, and which may help center a position of thefirst spring 154 relative to the first valve stem 152. Further, theperipheral flange 226 includes an outer circular edge 232. The secondvalve rotator 128′ is associated similarly with the second valve 124′.For clarity and ease, marking of only the first valve rotator 128 hasbeen provided. It will be understood that the second valve rotator 128′would include similar parts and references, with similar arrangement andfunctions, as has been described of the first valve rotator 128.

The guide structure 184 is configured to guide the valve bridge 136 withthe valve rotators 128, 128′ (and in turn with the valves 124, 124′)during each opening and closing of the valves 124, 124′. The guidestructure 184 includes a first guide 236 and a second guide 236′. Thefirst guide 236 and the second guide 236′ are respectively structuredand arranged on the base 186, at the first end portion 194 and thesecond end portion 196. As with the description above, for clarity, easein understanding, and referencing, further discussions of the guidestructure 184 will be divulged by focusing on the first guide 236 alone,and it will be understood that those discussions may be equivalentlyapplicable to the second guide 236′ as well. Wherever applicablereferences to the second guide 236′ may also be used.

The first guide 236 includes an integrally and contiguously extendingextension portion 240. The extension portion 240 extends partly fromeach of the first lateral face 200, the forward face 190, and therearward face 192, at the first end portion 194. As visualized byviewing FIGS. 2 and 3 together, the extension portion 240 may extendpartly outwards (termed as partly outward extension) from the base 186,and then partly downwards (termed as partly downward extension),according to orientations provided in the FIGS. 1, 2, and 3. In detail,the partly outward extension of the extension portion 240 issubstantially in a plane perpendicular to an axis 242 of first valvestem 152, while the partly downward extension is substantially parallelto (or along) the axis of the first valve stem 152. In brevity, theextension portion 240 may be visualized to be seamlessly, but partly,merged into each of the forward face 190, the rearward face 192, and thefirst lateral face 200.

The extension portion 240 includes a cavity 246. The cavity 246 isconfigured to accommodate the first valve rotator 128 and guide thevalve bridge 136 with the first valve rotator 128 during each openingand closing of the first valve 124 relative to the engine 102 (seedirection, C). In some implementations, the cavity 246 is circularshaped, and the first valve rotator 128 is substantially co-axiallyaccommodated within the cavity 246. When viewing FIGS. 2 and 3, thecavity 246 is defined upside-down, and in such an orientation, thecavity 246 may receive and accommodate the peripheral flange 226 of thefirst valve rotator 128 in a plane substantially perpendicular to anaxis 252 of the cavity 246 (also in line with the axis 242 of the firstvalve stem 152). The extension portion 240 includes a peripheral edge248, which is structured so as to encompass or surround the outercircular edge 232 when assembled. Further, the peripheral edge 248 isformed to merge into the valve bridge stem 182. To this end, theperipheral edge 248 may be continuous, extending from a portion of thevalve bridge stem 182 at the rearward face 192, and merging into aportion of the valve bridge stem 182 at the forward face 190 (best shownin FIG. 3). The peripheral edge 248 may be formed along the plane thatis substantially perpendicular to the axis 242 (or the axis 252 of thecavity 246). A clearance gap may exist between the peripheral edge 248and the outer circular edge 232 to accommodate a rotation of the firstvalve rotator 128, during operation.

In some implementations, a height H1 of the peripheral edge 248 may bebased upon a height H2 of the outer circular edge 232. In anotherexample, if the engine 102 is generally subject to relatively increasedvibrations, a peripheral edge with a relatively increased height H1 maybe applicable. This is because a heightened peripheral edge 248 may havea higher degree of contact surface area or positive contact surface withthe outer circular edge 232 of the first valve rotator 128, thusrestraining a disengagement between the first valve rotator 128 and thevalve bridge 136. In some implementations, the heights H1 and H2 may besubstantially same.

Moreover, the cavity 246 and the recess (first seat 206) define astepped configuration (see FIG. 2) and together form a profile of theguide structure 184 on the base 186, at the first end portion 194. Thestepped configuration of the cavity 246 and the recess (first seat 206)may in concert help guide the valve bridge 136 with the first valve 124,during operation. To this end, the recess of the first seat 206 and aninner contour of the cavity 246 may be formed such that a relativelystrong positive contact is maintained with the end 210 and the outercircular edge 232, and therefore the valve bridge 136, during engineoperation. In some implementations, the recess (first seat 206) and thecavity 246 are circular shaped. In such a case, the recess (first seat206) includes a first diameter and the cavity 246 includes a seconddiameter, with the first diameter being lesser than the second diameter.In such a case, the recess (first seat 206) and the cavity 246 may beco-axial to each other, as well.

In some implementations, exhaust valves, such as the first exhaust valve124 a, of the valve system 104 may also work in conjunction with a valvebridge 136′, similar to the valve bridge 136. In some implementations, agas exchange within each cylinder of the engine 102, such as cylinder108, may be facilitated with one or more of such valve bridges, as well.

INDUSTRIAL APPLICABILITY

During operation, as fuel is combusted in the engine 102, the piston 114executes a linear stroke which is translated to a rotary movement of thecrankshaft 120. Since the crankshaft 120 is coupled to the camshaft 130,the camshaft 130 rotates according to a rotation of the crankshaft 120and angularly varies the cam lobe 132 to move the cam roller portion 158of the rocker arm 134. Consequently, the opposite end 168 of the rockerarm 134 oscillates inversely in relation to a movement (or anoscillation) of the cam roller portion 158. Since the rocker arm 134 isslidably abutted to the valve bridge 136, the reversed oscillation istranslated to a reciprocatory movement (see direction, C) of the valvebridge 136 and the valves 124, 124′, relative to the engine 102. In someimplementations, a single articulating motion (or stroke) imparted tothe valve bridge 136 by the rocker arm 134 at the tappet head 176 mayresult in a lifting (open position) of the valves 124, 124′ by about thesame amount and at about the same timing. At every such instance of therocker arm 134 transmitting motion to the valve bridge 136, the elephantfoot 172 may slide against the tappet head 176, causing a dynamic change(see direction, D) to a point of contact 250 between the two components.Such dynamic change to the point of contact 250 may in turn lead to thedistribution of unequal forces in the valve bridge 136.

To counter conditions, such as a tilt of the valve bridge 136, arisingout of unequal force distribution, the cavity 246 may be configured toaccommodate and guide the valve bridge 136 with the first valve rotator128 during each opening and closing (see direction, C) of the firstvalve 124 relative to the engine 102. In either of the closed positionor the open position, since the peripheral edge 248 of the first guide236 encompasses the outer circular edge 232 of the first valve rotator128, and since the first valve rotator 128 may be retained within thecavity 246 by the relatively strong positive contact of the cavity 246,a dislodgement and a consequent tilt of the valve bridge 136 may be wellavoided. As a result, conditions such as a dropped valve, that mayotherwise damage the engine 102, is well avoided.

In some implementations, the recess of the first seat 206 may be absent,and the end 210 of the first valve stem 152 may be unable to be extendedor inserted into the first seat 206 to retain the valve bridge 136.Instead, the end 210 may be abutted against a flattened surface, flushin relation to a surrounding surface of the base 186, as aforementioned.In such a case, the extension portion 240 may solely retain and guidethe first valve rotator 128 against a dislodgement from the valve bridge136.

It should be understood that the above description is intended forillustrative purposes only and is not intended to limit the scope of thepresent disclosure in any way. Thus, one skilled in the art willappreciate that other aspects of the disclosure may be obtained from astudy of the drawings, the disclosure, and the appended claim.

What is claimed is:
 1. A valve bridge for a valve system of an engine,the valve system including one or more valves and a valve rotatorcoupled to the one or more valves, the valve bridge comprising: one ormore end portions; a seat formed at the one or more end portions toreceive the one or more valves; and an extension portion extendingoutwardly from the one or more end portions and defining a cavitytherein, wherein the cavity is configured to accommodate the valverotator, and guide the valve bridge with the valve rotator during eachopening and closing of the one or more valves relative to the engine. 2.The valve system of claim 1, wherein the seat includes a recess formedat the one or more end portions.
 3. The valve bridge of claim 2, whereinthe cavity and the recess define a stepped configuration and togetherform a guide structure to guide the valve bridge with the one or morevalves.
 4. The valve bridge of claim 2, wherein the recess and thecavity are co-axial.
 5. The valve bridge of claim 2, wherein the recessand the cavity are circular shaped, the recess including a firstdiameter and the cavity including a second diameter, the first diameterbeing lesser than the second diameter.
 6. The valve bridge of claim 1,wherein the valve bridge includes a tappet head, a first arm and asecond arm radially extending away from the tappet head to respectivelydefine a first end portion and a second end portion, the first endportion and the second end portion defining the one or more endportions.
 7. The valve bridge of claim 1, wherein the one or more valvesare one or more gas exchange valves.
 8. The valve bridge of claim 1,wherein the valve rotator is disk shaped and is configured to beaccommodated in the cavity along a plane substantially perpendicular toan axis of the cavity.
 9. A valve system for an engine, comprising: oneor more valves; a valve rotator coupled to the one or more valves; and avalve bridge including: one or more end portions; an extension portionextending outwardly from the one or more end portions and defining acavity therein, wherein the cavity is configured to accommodate thevalve rotator, and guide the valve bridge with the valve rotator duringeach opening and closing of the one or more valves relative to theengine.
 10. The valve system of claim 9, further comprising a seatformed at the one or more end portions, the seat configured to receivethe one or more valves.
 11. The valve system of claim 10, wherein theseat includes a recess formed at the one or more end portions.
 12. Thevalve system of claim 11, wherein the cavity and the recess define astepped configuration and together form a guide structure to guide thevalve bridge with the one or more valves.
 13. The valve system of claim11, wherein the recess and the cavity are co-axial.
 14. The valve systemof claim 11, wherein the recess and the cavity are circular shaped, therecess including a first diameter and the cavity including a seconddiameter, the first diameter being lesser than the second diameter. 15.The valve system of claim 9, wherein the valve bridge includes a tappethead, a first arm and a second arm radially extending away from thetappet head to respectively define a first end portion and a second endportion, the first end portion and the second end portion defining theone or more end portions.
 16. The valve system of claim 9, wherein theone or more valves are one or more gas exchange valves.
 17. The valvesystem of claim 9, wherein the valve rotator is disk shaped and isconfigured to be accommodated in the cavity along a plane substantiallyperpendicular to an axis of the cavity.
 18. A valve bridge for a valvesystem of an engine, comprising: a tappet head, a first arm and a secondarm radially extending away from the tappet head to respectively definea first end portion and a second end portion; a seat formed at each ofthe first end portion and the second end portion, and configured toreceive a gas exchange valve of the engine; and an extension portionextending outwardly from each of the first end portion and the secondend portion, each of the first end portion and the second end portiondefining a cavity therein, wherein the cavity is configured toaccommodate a valve rotator coupled to the gas exchange valve, and guidethe valve bridge with the valve rotator during each opening and closingof the gas exchange valve relative to the engine.
 19. The valve systemof claim 18, wherein the seat includes a recess formed at the first endportion and the second end portion, the recess being co-axial to thecavity.
 20. The valve system of claim 19, wherein the cavity and therecess define a stepped configuration and together form a guidestructure to guide the valve bridge with the gas exchange valve.